Wire-feebing mechanism for arc welding machines



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2 Sheets-Sheet 1 M. L. MacRAE Inventor: Muhgo L. Mac Rue, bg W f' His Attoheg WIRE FEEDING MECHANISM FOR ARC WELDING MACHINES Oct. 29, 1929.

Oct. 29, 1929. M, L, MacRAE 1,733,812

WIRE FEEDING MECHANISM FOR ARC WELDING MACHINES Filed NOV. 29. '1927 2 Sheets-Sheet 2 imm EN i Inventor' z MLU-1go L. MaCRae,

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tic isv the voltage across-the arc'.

Patented Oct. 29, 1929 l Unifran'fsrnres PAIENT Erica MNCO Il.4 M'A'CEAEO'E sCIIENECTADx. `NEW YoEK, AAssICfNoE To GENERAL ELECTRIC u y.ctaiirryaivrm A CORPORATION oE NEW YORK .Y

WmE-EEEDINIYIECIIANISM ECE AEC WELDING MACHINES -Myiinvention relateslto Wire feeding mechanism which is "of particular utility 1n automatic arc--weldingf'machines for feeding an ,electrode toward zand away 'from the Work tocon'trol the'welding arc' during the Welding operation;v f "7 'Automaticarc weldingfm'a'chires are now well linown.I IIn-suchmachines the welding arcis ordinarily struck andfmaintaned between 'thework to be welded and an electrode which 'ajsit4 is consumed is automatically fed towardthe 'work so that'the yaicis maintained at a substantially constant length. .In order to secure this operation it-is customary to regulate the rate at which the electrode is fed in accordance with an electrical characteristic of the arewhich-'vaifies with andis a measure of the arc length. l ,Suclfi a suitable l characteris- IVhere the welding current'varies substantially inversely-with'the voltageacros's the-arc such variations incurrent may be used tol govern the rate l of feed. Other arrangements may --be used such as combinationsof voltage and current control.v Y; y

In automatic machines for metallic arc wcldingwhere the eiectrode fuses rapidly and is incorporated inthe' weld it is desirable to provide the electrode in the form of a wire of indetinite length Awhich may be drawn from a reel'as it is us'ed.4 Thevelectrode may, however, be used in short lengths as is' always the case where substantially non-'consuming electrodes such as carbon are used.

It is customary to provide electrode feed rolls which grip the electrodeand feed it forward as it is consumed. These feed rolls are usually vdriven through reduction and variable speed gearing by an appropriate feed motor. According to one arrangement a variable speed motor is used. In this arrangementthe speed of the motor is automatically Variedin accordance with an electrical characteristic of the arc that varies with the are length and the arrangement is such that the feed motor by varying its speed operates in a manner to maintain the arc length substantially constant during the welding operation It is also old in the arti to operate such electrodefeeding-mechanism from a -constant *applica/cimmed November 29, 1927. serial No. 236,531.

speed driving means and regulate the rate of electrode feed by a speed regulating mecha' nism arranged between the constant vspeed driving means and the electrode Vfeeding means. 55':

lIn most ofthe machines of the prior art the motor is connected to thefeed rolls through speed reducing gearing since it has been found desirablc to operat-cthe motor used to drive the feeding mechanism at a comparatively high rate of speed while the feed rolls of the' feeding mechanism must of necessity turn at a lower rate of speed to feed the electrode toward the work as it is consumedv in the arc.' Changed speed gears are likewise-used since 'v the speed at which the electrode is fed must be greater for small electrodes than for larger electrodes and 'changes in speed are necessitated by the use of diit'erentcurrent densities and correspondingly different ratesof metal l deposition;

An object of my invention is to provide aniinproved wire feeding mechanism which =is of particular utility' in welding machines' hecause of its simiplicity and effectiveness and because it produces within itself an inherentl speed reduction. 1

A further object of my invention is to provide a feeding device in which a threaded feed roll rotated about an axis substantially parallel to the line of wire feed is caused to engage the electrode wire and feed it by reason of a screwlike engagement therewith. l

A further object is to provide means for ro tating said feed roll about the wire being fed during the feeding operation at a rate-of speed such that there is substantially no slippingac tion between the feed roli and the wire dur ing the feeding of the electrode.

My invention will be better understood from A the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

In the drawings Figs. A1, 2 and 3 show a sec tion and two detail views, one of which is part- 5 ly in section, of a feeding mechanism accord-v ing to my invention. Fig. 4 shows a semiautomatic welding machine, partly in sec# tion, and Fig. 5 a section of a welding head which forms a part of an automatic arc 'Weld- 100` shafts joined at 6 byI universal joints which l also serve to hold the spindles in'place in the spindle casing 7. The spindle casing 7 keyed to a hollow shaft 8 formed of two parts joined by a crank section S upon which is mountedan electrode guide memberlO. This shaft isA located within a-casing 11 in bearings.1 carried ,byend covers 12 for this easing.

. Casing 11 may form a part of the usual weldinghead ofthe automatic'or semi-automatic machine or may be secured thereto in any convenient manner. The spur gears 5 mesh with astationary circular rack 13 positively secured, together; with an oil guard ring 14, between Vthe 'top-cover, 12 and the' casing 11, Shaft 8; is rotated by a worm wheel lkeyed thereto and driven by worm 16 mountedon a shaft 17 positively connected tol the feed motor shaft 18 by a coupling 19. The feed rolls 1 maybe moved to andfrom each other aga-mount sufficient to .accommodate various sizesof electrode wire by an adjusting nut 20lwhich has an .inside conical surface at its lowenfedge in engagement with corresponding conical surfaces on bearings 21 which support the .-lower ends of the spindles 4 to which the feed rolls are attached. The universal joint in the spindles and the open construction lof the lower part-of the spindle casing readily permits this adjustment.

The operation is as follows: Electrode wire iszfed through the upper end of the hollow shaft 8 to` feed rolls 1 which are adjusted toward each other by adjusting nut 20 so as to firmly grip the wire between the screw threads 2. At this point the guide member 10 holds the wire in a central position with respect to the feed rolls. From the rolls theelectrode is fed through the lower end of shaft 8=to a nozzle (not shown) which directs theelectrode to the work. The welding current is conducted to the electrode in any convenient manner. The electrode feed motor 4@lot shown) is connected in any known mannel.' responsive to some electrical characteristic'of the. arc so that its speed is so regulated as to .feed the electrode at a rate corresponding to its consumption in the are. This motor rotates the worm 16 which revolves the spindle casing 7 through worm wheel 15.. .As the casing revolves gears 5 attached to the spindles 4 aie rotated by their engagement with the stationary rack 18. Thustheelectrode feed rolls-.1 rotate about their own axes and also about the axis of shaft 8.

It is not necessary to my invention that the feed rolls be bodily rotated about the wire being fed but I prefer this arrangement since under certain conditions by rotating the feed rolls bodily about the wire at the proper rate of speed all slipping action between the feed rolls and the wire is elminiated and better results v are secured.' I'f the vrolls are not rotated bodiy about-the'wire and if the wire is not free to rotate as will be the case when withdrawn'from a stationary reel the threads on the rolls- Twill form-notches in the wire spaced 'from one another the pitch of the screw threads-which act through these notches to feed the wire relative to the feed rolls on which the threadsare located. There is, however,..under these conditions a wiping or slipping action 'between the Wire and the rolls which tends to rotate the wire. The excessive friction losses 'resulting from this slipping action necessitate the use of more power than would be required if the feed rolls were bodily rotated about the wire and if the feed rolls are rotated bodily about the Wire at theproper rate of speed this slipping action may be entirely eliminated. Vhen the threaded rolls are rotated about the wire at the proper rate of vspeed spaced circular grooves are -formedlon the wire which are spaced from one another the pitch of the screw thread. The thread which forms these grooves likewise engages 4them and feeds the wire relativ-e to the feed roll on which the thread is located to or from the work dependingon the direction of rotation of the feed roll.

Itis preferable to have several sets of feed rolls with threads of different pitches for any givenmachine which may be used as desired to securevarious rates of electrode feed for any given speed of the feed motor. With any given set of rolls the speed of wire feed may be varied by varying the speed of the feed motor. By using several sets of feed rolls and by electrically adjusting the speed of the feed motor over a limited range with any given set of feed rolls it is possible to adapt one machine for a variety of speeds of Wire feed without resorting to variable or change speed gearing. The adjustment of one feed roll relative to the other also enables the feeding mechanism to accommodate wires of various diameters.

In Fig. 4 I have illustrated my invention as applied to a. portable semi-automatic are welding machine such as described and claimed in Letters Patent of the United States No. 1.508,711 granted September 16. 1924 to Paul O. Noble and assigned to the same assignee as the present case. The apparatus illustrated comprises electrode feeding mechanism 22, .according to my present invention, a motor 23 for operating the feeding' mechanism, a welding tool 24 to which an electrode 25 is adapted tobe fed and a flexible metallic tube 26 for guiding the electrode` from said feeding mechanism to thev welding l tool. The motor and feeding mechanism are supported in a partially enclosing casing 28 provided with a handle 29 and a base 30 which may conveniently be an electromagnet which whenexcited will firmly attach the casing to a magnetic supporting surface. The motor 23 is shown as connected to the feeding device 22vthrough gears 31 although it will be understood that by aligning the feeding device. with the feedmotor and feeding the electrode through a hollow motor shaft these gears may be eliminated.

The motor .23 lmay be a variable speed motor connected so as to be .responsive to a characteristic of -the arc which varies with its length and thus vary its speed with changes in arc length in ajmanner to vary the rate of electrode feed to-keep the arc length constant. For example, the motor may be electrically connected across the are and be responsive to arc voltage. The voltage of an arc varies with its length and thus if the arc tends to lengthen then the voltage impressed on motor 23 will increase and consequently the s peed will increase, thus feeding the elect-rode at amore rapid rale to reestablish the .original are length. `As the arc length shortens the reverse operation will take plaee. When such an arrangement is used the operator is not required to be as skillful as. where a constant speed motor is used to feed the electrode since when a constant speedmotor is used dependence must be had on the skill of the operator for main taining the arc length substantially constant.

The welding head shown in Fig. 5 is generally of the t pe shown in reissue Letters Patent of the nited States to Frank L. Sessions, No. 14,927, granted July 27, 1920 where a constant speed motor is used as the driving means and the rate of electrode feed is reguv ated by a speed regulating means arranged between the constant speed driving means and the electrode feeding mechanism.

In Fig. 5 theconstant speed feed motor 32 is built into the .welding head and operates through means comprising a clutch 33 to drive electrode feedingrolls 34 'forming part of my improved feeding mechanism, one embodiment of which has already been described.-

The stator 35 of the feed -motor 32 is clamped between parts 36 and 37 of the Welding head casing andthe rotor member 38 is supported on a hollow shaft 39 supported at its right by the partv 36 of the welding head casing. The rotor member is provided with a combined gear and clutch element 40 at its left. whichthrough gears 41 and 42, a gear not shown locatedbackfof gear 42, gear 43 (shown partlyindotted lines)l and gear 44 drives in arotational direction oppo-site to itself a clutch element 45. Gears 41 and 42 are supported on a shaft 46 supported in casing 37. The gear not shown in the drawing and the gear 43 are supported on a shaft. not shown in the drawing, which is located back ofthe shaft 46. Gear 44 and clutch element 45 are supported on-hollow-shaft 47 supported as the other shafts already referred to in casing 4part 37. On a shaft 48 supported within the hollow shafts 39 and 47 is a clutch'element 49 which may be moved into engagement with either clutchelement 40 or 45'by a longitudinal movement 'of the shaft 48 produced by the movement of. an arm50 which is under theiniluence of two operating coils 51 and 52 forming part of the welding head.

Coils 51 and 52 may be energized by the operation of a contact making voltmeter responsive to the-arc voltage as disclosed in Letters Patent of the United States to Wilbur L. Merrill, No. 1,541,582, granted June 9, 1925, and assigned to the same assignee as the present case. According to this arrangement one coil will be energized when-the are length is too great and the other coil energized when the arc length is too short, thus depending on are conditions clutch element 49 will be brought into engagement with either clutch elements40or 45 and shaft 48 will be rotated in one direction or the other to control the electrode feed. l n

`Connected to the left end of shaft 48 is a gear 53 meshing wiltha gear 54 mounted on the same shaft as worm 55 which engages worm wheel 56 ofthe feeding mechanism. The arrangement is best shown in the sectional view of Fig. 8. The feeding mechanism is thus rotated in one direction or the other depending on the rotational direction of shaft 48.

The feeding mechanism is supported on a. hollow spindle 57 supporte'din' easing part 58 attached to casing part 37 by means of a slip joint 59. A The attachment is such that casing part 58 may be rotated relativeto Acasing part 37 about the axis of shaft .48. The feeding mechanism is rotated about the hollow spindle 57 by worm wheel 56 .and the electrode wire 60 is fed through a bellmouth guide member 61 insertedin casing part 62 and through the hollow spindle` 57 bythe feed rolls 34 which are rotated about their own axes by ears 63 and 64 'and about the wire by a mem er 65 which is driven by wormwheel 56 and upon which-they are pivotally supportedv at66 and 67 (see Fig. 7). Gears 63 and 64 mesh with a gear 68 attached to or forming a part of hollow spindle 57 which is a stationary member and as the feed rolls 34 and gears .63 and 64, which are connected by shafts 69 and 70 with the feed rolls, are robrackets 71 and 72'the feed rolls will be given a'rotary lmotion about their own axes. 'The feedi-rolls are forced into engagement with the electrode by a spring 73 which acts through brackets 71 and 72. The tension of the spring may be regulated by a screw 74. Member 65 is steadied by a member 75 engagingcasing part 58 and the weight of the feeding means -is supportedupon a thrust bearing76'. The casing part'62 forms a cover for part 58 which may be raised 4or removed wheniit is Vnecessary to changeA the feed rolls 34. The cover is supported'onfpins extending through bosses-77 (best shown in Fig. 6).

The welding head may be secured in the welding machine in various manners. As illustrated,r it is supportedv from a part 78 of the welding `machine by a bolt-79 about which it may be swung and clamped in an adjusted position-by bolt 80. A handwheel 81 is provided-,for rotating shaft 48 inI order to thread` the electrode 60 through the welding head when preparing it for operation or for controlling the electrode when the headv is deenergized.

The operation of the Welding head just described is as follows: The head is swung about boltA 79; and the feeding mechanism adjusted relative to the body part of the head at 59 so that the electrodeis directed inthe desired di'- rection. 'Electrode-60 is threaded through the feed rolls- 34 and through hollow spindle'57 by opera-ting handwheel 8l which rotates shaft 18 which is gear connected to the feedl ing mechanism. The machine may then be put inoperation. Depending upon the are voltage, as 'has previously been explained, either coil 51er 52 willbe energized and cause clutch element 49 to en age either clutch element 40 or 45. These c utch elements, as has been explained, rotate'in opposite directions and hence shaft 48Will be rotated in opposite directionsA to operate the feeding means to feedthe electrode to or from the work. Thus while 'the fe ed motor 32 isoperating at con-.

stant speed d ue to the speed regulating mechanisxn forming part 'of the head the electrode is fed to and from thework in a. manner to strike and maintain the welding arc. t l t is thus seen that I have provided' an improved electrode feeding mechanism 'operable by a variable speed motor, the speed of which. is automatically vari'edin accordance withan electrical characteristiclof the arc "or by a constant speed mot-or, the speed of the electrode feed being regulatedvby the transmission mechanism. It will also be apparent that the electrode feeding means is of general utility and may be applied togas welding machines and that it maybe used to feed wire in apparatus other than welding machines..

The embodiments of the invention illustrated herein'have been selectedfor the purpose of clearly setting'fforth 'the principles involved. 1It will'be apparent, however, that the invention is susceptible of being'modiied to meet the different conditions encountered in use without departing from my inventionV and I therefore aim to cover by the appended claims all modifications within thetrue spirit and scope ofmy-invention.v

What I ciaim as new and desire to secure by Letters 4Patent ofv the United States, is:

1. An electrode feedingmechanism for automatic arc welding machines comprising' a threaded i feedl 'roll supported for rotation A about an axis substantially parallel to 4the line of-electrode Sfee'd, means for 'forcing said feedi roll into engagement with the electrode and-means for positivelyrotatingsaid feed roll. i f f An 5electrodefeeding mechanism for automatic aroweltling machines comprising'a threaded feedfroll supported for rotation about an axis substantially parallel" to vthe lino of=electrode feedme-ans-for forcing said feed roll into 'enga,:1;ement=withtheelectrode, means for driving saidi'feed rolltorotate it about its axis of rotation, an'd'fmeans responsive to a 'characteristic' -of the arcthat varies Witn' the are length for controlling' the operation of saidfeedroll'-tofmaintain' the are length substantially constant.

An electrode feeding mechanism for automatic arc welding machines comprising a'fpluraity of similarly threaded 'feed rolls, means for forcing4 said -feedrolls ito'engagement with the eiectrod'e," means for supporting said'feedrolls'for rotation about an axis substantially parallel 1 to -the 'fa-'xis'pf the velectrode, landmeansifor simultaneously rotating said feed rolls "aboutttheir' own axes and bodily about the electrode. f

41 A wire feedingl mechanism comprising a plurality-of similarly threaded 'feed rolls, mea nsfor'forcing' said" feed rolls into engagement withtlie wire to be lf'ed, means for supporting said rolls forrota'tion about axes -substantially parallel'to the axis of; thel Wire, means for rotating'said supporting means about thewirc, and meansfor simultaneously rotating said feed rolls.A

5. A wire feeding mechanism comprising a'threaded feed" roll', ineans'for forcing said feed roll into engagement' with the surface of the wire to be fed, means'forrotating said fee-:l: roll about its axis-'to feed t-he wire, and means forrotatingfsaid feed roll about the wire as an aXi's--"atfsucli a rate of speed that there is substantially no slipping action between -the feed roli and the' wire.

V6. An electrode feeding mechanism for automatic are welding-:machines comprising a threaded feed roll, meanstfor forcing said feed roll linto l'engagement with't'he electrode, means responsive tio'a 'characteristic of the arc that varies with the are Alength for positively rotatingsaid 'feed-roll at speeds such as VWili feed'fthel electrode to maintain the arc` lengtlrsbstanti'ally constant, and means 'for' simultaneously rotating said feed roll about the electrode as an axis at a rate of speed such that there is substantially no slipping action between the feed roll and the electrode during the feeding of the electrode.

7. An electrode feeding mechanism for arc welding machines comprising electrode engaging means, a driven shaft for operating said e ectrode engaging means to feed the electrode to or away from the Work, a substantially constant speed feed motor, a hollow shaft for supporting the rotor of said feed motor as well as said driven shaft, a

clutch element mounted on said rotor, a second clutch element mounted on a second hollow shaftthrough which said driven shaft extends, means for driving said clutch element from said rotor in a direction opposite to that of said first-mentioned clutch element, go a third clutch element secured to said driven shaft and located between said first-mention ed clutch elements and means for shifting this clutch element into and out 0f angagement with the other clutch elements in response to a characteristic of the are that varies with the are length whereby the rate of electrode feed is controlled in a manner to maintain the are length substantially constant.

8. A machine comprising a power shaft,

S0 wire feeding mechanism driven by said power shaft, means for rotating said wire feeding mechanism about the wire to be fed, means for supporting said feeding mechanism, and means for adjutably attaching said supporting means and said rotating means in the machine for rotation about the power shaft as an axis.

9. A machine comprising a power shaft, wire feeding mechanism driven by said 4G shaft, a spindle whose axis is substantially parallel to the line of wire feed, means for supporting said feeding mechanism for rotation about said spindle, a support for said spindle and means for attaching said support in said machine so that it may be adjusted relative thereto about an axis coincident with the axis of the power shaft.

In witness whereof, I have hereunto set my hand this 28th day of November, 1927.

MUNGO L. MACRAE. 

